Buzzing noise

I have tried the hood adjuster trick, the flaps (both sides in wheel well) none worked. I agree with a few posts as it sound like it in the dash or steering wheel. Funny thing is it is intermittent and speeds around 45. I now Always listen for it but have not figured it out yet. Been going on for just about a year. If anyone figures it out please post. I heard a recording from someone's previous post and it was identical to my same noise. It's a buzzing/ rattling noise. Sometimes starts out very soft sounding then increases in sound. But you need to have the radio very low and A/C on lower speed